Authors note that fictional characters have a tendency to take on a life of their own. But few readers realise just how literally they mean it. A friend of mine, engaged in writing a romantic novel, called me in a panic just a year ago to complain that two of her characters had just run off and got married… thus ruining her carefully-crafted plot.

In theory this should not have been a problem. From her god-like perspective, the writer could surely have deleted the relevant passage and written a new one that put her creation back on track. In practice, any attempt to rein in characters like that will produce an almost unreadable novel, full of wooden dialogue and contrived situations. The only viable answer is to let them go their own way, abandon any preconceived plot notions, and see what ‘really’ happens.

The popular American science-fiction writer, Ray Bradbury, was so intrigued by the phenomenon that he wrote it into one of his own books. The Martian Chronicles describes how visitors to the red planet are confronted by characters from classical fiction who had somehow taken on corporeal existence in the alien environment.

Curiously, Bradbury’s idea – that fictional characters might, in certain circumstances, take on solid form – had widespread currency in Tibet. Such creatures were known as tulpas and at least one European traveller claimed to have seen them.

Madame Alexandra David-Neel, a distinguished French academic and explorer who died in 1969, reported that while camped in the Tibetan highlands, she was visited by a young painter she knew vaguely from a previous stay in Lhasa. The man had a particular obsession with one of the many Tibetan gods. For years he had meditated daily on the deity and painted its image many times. As he entered the camp, Madame David-Neel claimed she saw a misty representation of the god hovering behind him.

She was so intrigued by this phenomenon that she studied Tibetan teachings about tulpas and eventually decided to create one for herself. To this end, she visualised a cheerful brown-robed monk, based loosely on Friar Tuck in the Robin Hood legends. After weeks of effort, the imaginary monk became so vivid that he appeared to her as if he were physically present – an induced hallucination.

But then, says Madame David-Neel, the monk began to turn up when she was not trying to visualise him. Furthermore, his appearance was changing: he grew thinner and developed a sly expression. When other members of her camp asked about the ‘strange little lama’ she decided the time had come to destroy her creation… and battled for weeks before finally managing to do so.